Friday, September 19, 2014

How to Make a Waterwheel

Everything today runs on batteries and electricity, but let's face it, that just wasn't the case back in the good 'ol days. The Romans used waterwheels as far back as the 4th century AD. The most popular application is at mills, grinding grain into flour.

To show my son what the power and force of moving water was capable of, we made a model of a waterwheel. 

This activity was surprisingly simple and requires supplies you probably have on hand.

Empty plastic spool of thread
One (two if small) plastic disposable cups
Duct (or heavy-duty masking) tape
Empty 2-liter soda bottle
Strong thread or dental floss
Metal washer
Scissors (or a craft knife to be used by adults only)
Plastic drinking straw

1. Cut a strip from the middle of the plastic cup(s) that is the same width as your spool of thread. Cut one rectangle from the strip about 1 1/4 inch from the cut edge. Use this rectangle as a pattern to cut rectangles of the same size from the strip until you have 6 rectangles. These are the blades of your wheel.

2. Tape the blades onto your spool making sure to evenly space them, and that all the blades are curved in the same direction.

3. Thread the drinking straw through the hole on the spool. Position the waterwheel in the middle of the straw and use more tape to secure the spool in place on either side with more tape. Set aside.

4. Now cut the top from your empty 2-liter bottle of soda. You can use the top of the label on the bottle as a guide for where to cut. You'll want to have a tall cylinder. (Note: Adults should help or do the cutting. This is tough!)

5. Adults: Poke holes in the bottle about 1 inch from bottom for drainage. I used a craft knife to do this.

6. Cut a V shape in the top of the cylinder. Cut another V directly opposite it.

7. Now tie a strand of heavy thread or dental floss that is about 12-15 inches long to one end of the drinking straw and tape in place so it doesn't slide around.

8. On the other end of the thread, tie a metal washer.

9. Now place the waterwheel's straw in the notches you made on the 2-liter and put the waterwheel under a facet.

10. Turn the water on slowly and watch the wheel turn, and the force of the water pull the washer up.

This great idea came from Kerrie Logan Hollihan's phenomenal book on Isaac Newton. Check it out!


  1. I love your hands-on learning ideas - and this waterwheel would be a huge hit at my house!

  2. This is a really cool project. We have an interesting book of engineering ideas at home, but we are yet to do anything from it :)